What is seasoned?

[Crazy Cutter]

Usually because they dont understand that burning any green wood is not efficient, and will still tar the chimney.

 

It just so happens that ash will burn green and is readily available so many people are led to think its a good wood to burn!

 

Lets just remember that when the firewood poem was made up and other sayings, the woodburner wasn't used here just huge open fires in the average country home. Logs were rare just big faggots which would have dried quicker than a log. We are the ones now who need to be telling people what is good to burn or suitable for woodburners. The customer is still thinking open fires with a mountain of coal to get it going! Hope that makes sense.

[shanks]

Anything under 25% goes on my fire, Pulled a fair amount of felled spruce off the hills from the FC this summer. Had been there a few years I would guess and was reading around 19% in the summer. Burns like a dream.

[farmer rod]

Someone pointed me to this Wood Equilibrium Moisture Content Calculator from Wood Workers Source.com in another thread.

 

If you live in the moist northern hills and are getting 20% you are not doing too bad!

 

So if you only buy well aged logs from Phoenix Arizona you can be assured that they are properly dry

[Pete Tattam]

Not very well informed on this but I would have thought if the wood is exceptionally dry it would burn faster, meaning having to use more wood over slightly less dry wood. Good for the suppliers perhaps but not so good for the punters. Also some woods burn hotter than others (is that calorific value?). I only produce very small quantities which I sell at low low prices to friends and neighbours so I follow the "tell em the truth" principle. I inform them what type of wood it is, how long it's been split and suggest if they should keep it a while longer before burning. Never had a complaint.

[skyhuck]

Not very well informed on this but I would have thought if the wood is exceptionally dry it would burn faster, meaning having to use more wood over slightly less dry wood. Good for the suppliers perhaps but not so good for the punters. Also some woods burn hotter than others (is that calorific value?). I only produce very small quantities which I sell at low low prices to friends and neighbours so I follow the "tell em the truth" principle. I inform them what type of wood it is, how long it's been split and suggest if they should keep it a while longer before burning. Never had a complaint.

 

No, your far better controlling the speed of burn by controlling the air supply.

[18 stoner]

Not very well informed on this but I would have thought if the wood is exceptionally dry it would burn faster, meaning having to use more wood over slightly less dry wood. Good for the suppliers perhaps but not so good for the punters. Also some woods burn hotter than others (is that calorific value?). I only produce very small quantities which I sell at low low prices to friends and neighbours so I follow the "tell em the truth" principle. I inform them what type of wood it is, how long it's been split and suggest if they should keep it a while longer before burning. Never had a complaint.

 

Each log has its own amount of calories, dry or wet.

 

If you burn the log wet, many of those calories are used up heating up and burning the moisture(steam and tar created)

 

If the same log were dryer, those calories could be released in heat out of the fire/stove.

 

A balance is needed though, as to not introduce decay as a result of the extra time needed to dry/season, as this will reduce its calorific value.

[openspaceman]

Yes the same was done when summer felling Sycamore for furniture timber, the leave continue to transpire (is that the right term??) so most of the sap is draw out reducing the chance of staining.

 

Never risked that, the saying was fell on Xmas Eve, transport on Xmas day and mill on Boxing day.

 

Oak was often felled in late winter, left at stump and extracted after the hay harvest and then milled in the Autumn so that initial drying in the stick was not too fast.

 

AJH

[openspaceman]

Someone pointed me to this Wood Equilibrium Moisture Content Calculator from Wood Workers Source.com in another thread.

 

If you live in the moist northern hills and are getting 20% you are not doing too bad!

 

I'm glad you found that, I think the equilibrium mc in my house is about 17% on a wet weight basis, the sawn timber trade often calculates on a dry weight basis and for wet wood there's a lot of difference.

 

The equilibrium mc is dealing with the water bound to cell walls and there is a small amount of energy in the bonding, so the emc is slightly different as a log gains moisture from when it loses moisture.

 

Essentially the free cell water is fairly easy to remove and the wood doesn't change much as it evaporates, the cell wall water loss causes the wood to shrink, mostly tangentially, less radially and little lengthwise. It's controlling this latter water loss that seasoning planks is all about, making sure moisture leaves the surface at exactly the same rate it can migrate from the inside. This is not an issue with firewood where a few extra fissures speed up the drying.

 

With hardwoods the point where the free cell water is gone can be demonstrated by blowing or sucking through the grain. I would consider wood with the free water gone to be seasoned for firewood.

 

I'd also caution reliance on hammer in probes as a good measure of mc of drying, as opposed to stable, wood because in summer the wood surface will dry much faster than the moisture can migrate from the middle. A quick test is to cut a bit from the middle and gently microwave it on a defrost cycle, weighing before during and after. A point will be reached just before pyrolysis starts in the middle which is the oven dry weight, subtracting this from the wet weight gives the water content. If you over do it you will not be able to use the microwave for cooking again

 

To do it properly the sample needs oven drying at 120C for 24 hours. Any more than this an volatile organic compounds will be lost, reducing the dry mass.

 

AJH

[Tom D]

I think there is a lot of guff talked n this subject, as big j says the flue temperature is the important factor, dry logs contain MORE tar by weight than wet ones, so smouldering dry logs will gum up a flue just the same as wet ones. Dry timber burns hotter and therefore warms up the flue quicker allowing tar vapour to escape the top of the chimney, also it gives out more heat to the room as less heat is wasted boiling off the moisture in the wood.

 

i think you will struggle to get lower than 20%mc drying outside and another factor is species, split pop will dry much quicker than split cherry, so if they are both in the same pile some logs will be dryer than others, I don't bother to measure the mc of my logs any more, lives too short. There are loads of guys selling green wood out there.... and very few selling sub 20%mc stuff. Mine will easily pass the pepsi challenge with most of the stuff around here. And thats all that matters, its about making money after all.

[Dean Lofthouse]

I thought tar was transported up the flue in the moisture vapour and the vapour condensed on the cold liner and depositing the tar. If there's no moisture in the wood the tar is burnt and not transported. But there is always moisture in wood so the less there is the less tar deposits there are, also if the liner is hot, the water vapour cannot condense

 

 

Sent from my iPhone cos it was